In the present day, solid state fault current limiters (SSFCL) are used to regulate current over transmission lines where transmission of currents of several thousand amps are common. SSFCL systems are designed to prevent excessive current in the event of a fault condition. In one design of an SSFCL, a mutual reactor is configured to split load current into a control leg and a limiting leg. The control leg may include power electronic switch(es) and may be designed to transmit a current well within the rating of power electronic switches, such as several hundred amps. The limiting leg may be designed to transmit several thousand amps and may be further designed with an adequate self-inductance to limit the prospective fault current to a desired safe level. Under normal conditions current flows in both legs of the mutual reactor, where the reactor is designed in this situation to have low losses. A circuit or similar component is provided to monitor the control current of the control leg, and to open the power electronic switch(es) when a current threshold (or other triggering scheme) is exceeded, so the mutual reactor becomes unbalanced, and the self-inductance of the limiting leg then reduces the current flowing in the limiting leg to a safe level.
One issue with the aforementioned design arises when solid state switches fail to short circuit. Since this circuit just opens the solid state switches on-fault, any failure of the solid state switches is just evident on demand for fault protection. The fault current limiter may include a fuse to protect against solid state switches failures or other component failures. One issue with fuse design is when the total current increases, the energy used to blow the fuse in the control leg may not be sufficient to protect a network from damaging first peak faults (i.e., at approximately 5 ms). Indeed, when the mutual reactor is designed to have less fault current let through than normal current (due to a high peak fault current reduction requirement for example), the fuse protection system can never work.
With respect to these and other considerations the present disclosure is provided.